This invention relates to an electrical switch having a unitary contact element pivoted around a stationary middle contact block and made of electrically-conductive material, said contact element being brought into or out of contact with stationary contact blocks in two stop positions by means of an actuating element, wherein the contact element simultaneously serves to produce a snap movement.
Switches of this type are used as throw-over switches, and they can be both unipolar or multipolar. In addition, especially in the case of rotary switches, there is the possibility of arranging several switch stages one behind the other and activating them simultaneously by means of a common stub shaft. Since these switches, which are used in electrical equipment, are needed in large quantities as so-called service switches, their design must be as simple as possible, while at the same time they must be suitable for multifarious uses. Moreover, the contact terminals are generally designed in such a way that the switches can be installed in the circuit board of a printed circuit.
To make the construction of the switches as simple and inexpensive as possible, the technique of using contact springs simultaneously to produce a snap movement has already been developed. Thus, in a known miniature switch suitable for mounting in the circuit board of a printed circuit, the actuating element bears a contact bridge which, in each switch position, rests under spring pressure against a middle contact block and a contact block, or, after movement over the cams of the middle contact block, rests against another contact block, wherein the contact bridge is designed as a spiral spring that rotates around a bolt-like pivot. The contact blocks and the middle contact block are connected electrically with the conducting elements of the printed circuit, while the pivot is only mechanically attached to the circuit board. The two ends of the spiral spring are bent outwardly, so that one end serves as the contact bridge, while the other end leads to the actuating element. A disadvantage of this switch is that it can be used only as a unipolar throw-over switch, and is thus limited to one application possibility.
Also known is a unipolar or multipolar slide throw-over switch consisting of a plastic housing from the bottom of which terminals project. The peak coil of a V-shaped wire spring serving as a contact bridge is loosely attached inside the housing by means of a middle terminal. The two equally long sides of the V-shaped wire which exert the spring pressure, alternately rest against one of the other two terminals, and all three terminals form a triangle. The wire spring only serves as a contact bridge, so that tongues or barriers formed on the sides of the slide bar and equipped with cams are needed for catching on the housing.